📷 L.jpg
Weird cross pattern showing up only in the Luminance data, This is about 9 hours of data, 300 s subs, 585 sensor, on the quattro 150p scope calibrated with flats and darks.
Anyone got a solution?
Cross pattern in Luminance channel
Engaging
It is a calibration issue. Check the consistency of your calibration masters, in particular between bias, dark and flats. You also have additive signal there.
andrea tasselli · May 2, 2026, 05:33 AM
It is a calibration issue. Check the consistency of your calibration masters, in particular between bias, dark and flats. You also have additive signal there.
I am not using Bias frames, only darks and Flats.
For flats i am using SkyFlats without any diffuser in between like a T shirt. The exposure time is 0.2s per flat.
Are your flats dark-subtracted?
andrea tasselli · May 2, 2026, 05:39 AM
Are your flats dark-subtracted?
You mean dark Flats?
No did not use dark flats
The problem is i never had this issue with any color camera.
Hassaan Zaheer · May 2, 2026, 05:42 AM
You mean dark Flats?
No did not use dark flats
You should. Always. Or bias.
And much longer flats for this particular sensor.
andrea tasselli · May 2, 2026, 05:46 AM
And much longer flats for this particular sensor.
Got it.
ill try longer flats
Hassaan Zaheer · May 2, 2026 at 06:50 AM
andrea tasselli · May 2, 2026, 05:46 AM
And much longer flats for this particular sensor.
Got it.
ill try longer flats
Yes, this should work and resolve the grid pattern.
another issue could be image registration in combination with noisy data. try playing with the interpolation algorithm in StarAlignment. CS Matthias
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